The present invention relates to a lamp cartridge utilized as a lighting device incorporated into an image displaying apparatus.
In order to ensure the safety of a metal halide lamp (arc lamp)or the like used as a high intensity light source for an image displaying apparatus and allow it to demonstrate the specification and performance thereof intended by its manufacturer, it is required to keep the temperatures at the specified portions on the metal halide lamp, a reflecting mirror, and so on at predetermined values.
FIG. 12 shows portions of a lamp 7, a reflecting mirror 2, and a supporting base 11 for the lamp 7 and the reflecting mirror 2 whereof the temperatures should be kept at predetermined values (predetermined values differ from portion to portion).
Reference characters 2a represent a neck portion of the reflecting mirror 2, and 7a, 7b, and 7c represent respectively a tip electrode, a bulb, and an end portion of the lamp 7, whereof the temperatures are required to be maintained at predetermined values, as well as the temperatures of the reflecting mirror 2 and the lamp 7.
Miniaturization of the image displaying apparatus requires miniaturization of the reflecting mirror 2, the lamp 7, the lamp supporting portion, the fan and so on which occupy a relatively large volume of the apparatus, and thus results in an inconvenience as described below
That is, in order to obtain at least the same intensity of illumination as the conventional apparatus, it is necessary to increase the intensity of the lamp when miniaturizing it. Therefore, the lamp emits superheat, and thus will need a high-power fan and a lamp supporting portion with sufficient heat resistant properties.
In addition, in a conventional exhaust mechanism or a mechanism for blasting cooling air by means of a nozzle, it is difficult to maintain predetermined portions stated above at predetermined temperatures, and thus the specification and performance of the lamp cannot be demonstrated, which will cause shortening of the lifetime, irregularity of the intensity of illumination, and deterioration of the color rendering properties of the lamp.
Furthermore, a conventional exhaust mechanism suffers from insufficient heat exhaust efficiency of the fan, and thus requires increase of the output of the fan which may cause a serious noise problem.
An object of the present invention is to provide a lamp cartridge of which components such as a lamp, a reflecting mirror, a lamp supporting portion, a fan and so on can be effectively miniaturized.
Another object of the present invention is to provide a lamp cartridge enabling the lamp to demonstrate its specification and performance sufficiently.
The lamp cartridge according to the present invention comprises a lamp being a light source, a reflecting mirror for converging light emitted by the lamp, a case for covering the lamp and the reflecting mirror and for supporting the reflecting mirror, and a fan disposed at a window on the side surface of the case covering the side of the reflecting mirror for exhausting heat from within the case. On one of the surfaces constituting the case from which the ray from the reflecting mirror goes out, a hole including the optical axis of the reflecting mirror and having a diameter smaller than that of the reflecting mirror is provided. In this arrangement, the air outside the case is introduced through the hole into the case so that heat generated by the lamp and the reflecting mirror is exhausted from the case by means of the fan.
The present invention also includes a lamp cartridge having a fan provided at the window made on the surface of the case behind the reflecting mirror.
The present invention further includes a lamp cartridge having a slit on the surface of the case on the opposite side of the fan, or on the surface of the case behind the reflecting mirror in the vicinity of the surface on the opposite side of the fan for introducing the outside air into the case therethrough and exhausting heat generated by the lamp and the reflecting mirror by means of the fan.
The present invention still further includes a lamp cartridge having a fan provided at the window made on the surface of the case behind the reflecting mirror, wherein at least one slit is provided on the side surface or surfaces of the case covering the side or the sides of the reflecting mirror in the vicinity of the surface of the case on the opposite side of the fan, or on the surface of the case on the opposite side of the fan for introducing the outside air into the case therethrough and exhausting heat generated by the lamp and the reflecting mirror by means of the fan.
The present invention still further includes a lamp cartridge having various kinds of structures as mentioned above, wherein the center of the hole from which the ray goes out is displaced relative to the optical axis of the reflecting mirror.
The present invention still further includes a lamp cartridge having various kinds of structures as mentioned above, wherein a louver for shading leakage light from the lamp is disposed between t he case and the fan.